Two countries, I think, as I'd wager the northern cousins are as guilty as we on this point. I can tell you that to the ears of people over here, there's a clear distinction between th' t in Plato and th' d in Play-doh, as you'd normally hear those names vocalized (pardon that zed!) here. But when I say them in quick succession, I'm struck by how subtle the actual sonic quality that renders them distinct really is. No surprise if it's a distinction lost on the rest of the English-speaking world. Funny thing, language.

An interesting argument, that it really is being pronounced correctly and just that everyone else can't hear it... I have no effective reply to that.

Other than it reminds me of a similar argument (get-out clause?), "you don't understand my argument, well you need to read more." This or, "we're coming at this from differing perspectives and thus neither are at fault" is an attempt to remove responsibility. It's an odd thing, I know, using terms like responsibility for our common language use, but I think we have one anyway. It is always (at the very least) partially our fault when language goes awray. Of course it becomes problematic when we attempt to frame quite how this responsibility will fit with our actions.